Chiri is right, there is no charge and you can access the beach there. I don't know if they really insist on buying from the restaurant or bar to use the chairs, might just depend on the whim of the staff at the moment. When I've been there I bought a beer to be polite and figured that was good enough, (I must admit though that one beer usually leads to several... lol.)
I've eaten at the restaurant(s).... Pulpo and the Steak house, a few times. As for the food, I didn't think it was fantastic, but it was between OK and good. Tourist prices of course. The service was sometimes very friendly and good, sometimes surly and slow. I didn't find it particularly dirty. The restrooms were serviceable, good by comparison to the usual public restroom in the D.R., and a little sketchy by U.S. standards.
Chiri... what are the other options in the area? Could go further down to los corales, by the Soles bar restaurant, and I think there's a beach access on the south/east side of Barcelo Dominican Beach... by the Beach Residency condo complex. Any others?